python - Pandas : A value is trying to be set on a copy of a slice from a DataFrame

Question

我在 pandas 中有一个非常简单的命令，例如:

volume_related_pd.loc[:,"last_record_volume"] = volume_related_pd.loc[:,"volume"]

我认为复杂性在于我有重复的索引。它会产生以下警告:

/anaconda2/lib/python2.7/site-packages/pandas/core/indexing.py:601: SettingWithCopyWarning: A value is trying to be set on a copy of a slice from a DataFrame. Try using .loc[row_indexer,col_indexer] = value instead

我该怎么办？谢谢。我已经使用 .iloc

Answer 1

哦。我发现...这来自volume_lated_pd 最初的定义方式。

一开始是这样的

volume_related_pd = complete_contract_info_pd[["volume"]]

然后警告出现。

但是，如果我专门将其定义为原始 pd 的副本，那么问题就消失了:

volume_related_pd = complete_contract_info_pd[["volume"]].copy()